Background: The relative contribution of biologic subtype to locoregional recurrence (LRR) in patients treated with neoadjuvant chemotherapy (NAC), mastectomy, and postmastectomy radiotherapy (PMRT) is not clearly defined.
Methods: 233 patients with stages 2 and 3 breast cancer who received NAC, mastectomy, and PMRT between 2000 and 2009 were included: 53 % (n = 123) had HR+ (ER or PR+/HER2-), 23 % (n = 53) had HER2+ (HER2+/HR+ or HR-), and 24 % (n = 57) had triple-negative (TN) disease (HR-/HER2-). The 5-year LRR rates were estimated by Kaplan-Meier methods. Cox regression analysis was performed to evaluate covariates associated with LRR.
Results: The median follow-up period was 62 months. A pathologic complete response (pCR) was seen in 14 % of the patients. The 5-year LRR rate was 8 % for the entire cohort. The LRR rate was 0 % for the patients with a pCR versus 9 % for the patients without a pCR (p = 0.05). TN disease [Hazard ratio (HR) 4.4; p = 0.003] and pathologic node positivity (HR 9.8; p = 0.03) were associated with LRR. Patients with TN disease had a higher LRR rate than patients with HER2+ or HR+ disease (20 vs. 6 and 4 %; p = 0.005). Among patients without a pCR, TN subtype was associated with increased LRR risk (26 versus 7 % HER+ and 4 % HR+; p < 0.001).
Conclusions: Patients with TN breast cancer had the highest LRR rate after NAC, mastectomy and PMRT. Whereas no LRR was observed among TN patients with a pCR, TN patients with residual disease had a significantly higher LRR risk. Patients with HR+ and HER2+ breast cancer had favorable LRR rates regardless of NAC response, likely due to receipt of adjuvant systemic targeted therapies.